DESCRIPTION: The role of androgen in the development of cognitive function and neural organization will be evaluated by studying patients with congenital adrenal hyperplasia (CAH), an autosomal recessive disorder causing increased androgen production beginning prenatally. One hundred fifty patients (50 male and 50 female) will be compared to unaffected relatives and to demographically-matched controls. Abilities to be assessed include visuospatial abilities, mathematical abilities, verbal abilities, targeting abilities and general intelligence. Manifestations of neural organization to be assessed include hand preferences and language lateralization. Three competing hypotheses regarding the relationship of prenatal androgen to cognition will be evaluated: 1. Androgen promotes cognitive abilities at which males excel on average (mathematical problem solving, mental rotations abilities, spatial perception and targeting) and impairs those at which female excel on average (verbal fluency and perceptual speed and accuracy); 2. Androgen is associated with general intellectual enhancement; and 3. Androgen is associated with discrepancies between verbal and performance intelligence that have been interpreted to suggest learning disabilities. Hypotheses that prenatal androgen exposure is associated with masculine- typical patterns of neural organization, reflected in reduced right hand preferences and increased language lateralization, will also be assessed. Finally, structural equation models will be used to examine relationships between sex-typed activities in childhood and subsequent patterns of neural organization and cognitive function.